There are numerous substances used today, both in the workplace and at home, which are difficult to remove once they adhere to a surface. As examples, commonly used materials include oil, grease, ink, paint, tar, caulking and sealing compounds, adhesives and glues, coal dust, pitch, varnishes, and so forth. These and like materials are often difficult to remove from the skin and other surfaces because they are not miscible in water and therefore not readily removed with common cleaners such as soap and water. In this regard, numerous cleaning compositions have heretofore been specifically formulated to help remove such materials. These cleaning compositions typically include one or more solvents that help to dissolve and/or solubilize many water-immiscible materials such as grease, inks and so forth.
However, many solvents are themselves immiscible in water. Nevertheless, stable and substantially homogeneous cleaning compositions containing water and water-immiscible solvents are well known in the art. The stability and homogeneity are often achieved through the use of one or more surface-active agents to form an emulsion. Terpenes, for example, are immiscible in water and are therefore commonly used in aqueous cleaning compositions in combination with one or more emulsifiers. As an example, aqueous emulsions using d-limonene as the solvent or cleaning component are described in Coleman, D-Limonene As A Degreasing Agent, The Citrus Industry, vol. 56, No. 11, November 1975. Coleman""s hand cleaning lotion, for example, includes water, d-limonene, lanolin and about 15% or more of several non-ionic surfactants. Similarly, U.S. Pat. No. 4,620,937 to Dellutri teaches an all purpose cleaner comprising a mixture of d-limonene, stearic and oleic acids, non-ionic detergents and water. In Dellutri""s preferred example, the non-ionic detergents comprise approximately 7.5% of the cleaning agent. In addition, U.S. Pat. No. 4,511,488 to Matta teaches a homogeneous aqueous cleaning composition including water, d-limonene, a coupling agent and 10 to 30% by weight of a surfactant. By utilizing the particular combination of ingredients, Matta forms a cleaning composition that is clear, homogenous and readily flowable despite the inclusion of a water-immiscible solvent such as d-limonene.
In addition, various cleaning articles have likewise been used in combination with liquid cleaners to aid in cleaning surfaces. By way of example, various wipes and cleaning articles are described in U.S. Pat. No. 4,100,324 to Anderson et al.; U.S. Pat. No. 4,436,780 to Hotchkiss et al., U.S. Pat. No. 4,659,609 to Lamers et al., U.S. Pat. No. 4,853,281 to Win et al., U.S. Pat. No. 4,833,003 to Win et al. and PCT Publication WO 00/56201. Further, saturated or pre-moistened papers, nonwovens, textiles and other substrates have been used in a variety of wiping and cleaning applications. Cleaning sheets or wipes are often provided in a sealed container and retrieved therefrom in a saturated or moist condition (i.e. pre-moistened). The pre-moistened substrate releases the retained liquid when used to clean the desired surface.
With regard to the foregoing liquid cleaners and articles, emulsifiers are often critical components of the same due to their ability to solubilize the solvent and also to help the cleaning liquid wet out hydrophobic surfaces. In addition, the emulsifiers likewise help loosen water-immiscible materials from the surface as well as solubilize the same thereby helping to keep them from being re-deposited upon the cleaned surface. However, many emulsifiers also have the undesirable affect of xe2x80x9cde-fattingxe2x80x9d the skin. In this regard, many emulsifiers draw fat from the skin and thereby detrimentally effect the skin""s ability to retain moisture. The xe2x80x9cde-fattingxe2x80x9d of skin by emulsifiers is a phenomena described in the following articles: Wilhelm, K., Prevention of Surfactant-Induced Irritant Contact Dermatitis, Current Problems in Dermatology, vol. 25, pp. 78-85 (1996); Morganti, P., Natural Soap and Syndet Bars, Cosmetics and Toiletries Magazine, vol. 110, (November 1996). Thus, exposure to significant amounts of emulsifiers can result in dry and/or damaged skin.
While there exists a wide range of aqueous cleaners and/or cleaning articles that incorporate one or more water-immiscible solvents, there remains a need for aqueous cleaning compositions and articles containing the same that effectively clean while limiting the physical and/or chemical disturbance to the skin. Further, there remains a need for such articles incorporating such cleaning compositions that contain an effective amount of the cleaning composition. Still further, there remains a need for such cleaning compositions and articles incorporating the same that have good shelf lives and can be made safely and economically.
The aforesaid needs are fulfilled and the problems experienced in the prior art overcome by the cleaning articles of the present invention which comprise a porous material containing an aqueous cleaning composition and wherein the aqueous cleaning composition comprises (a) at least about 25% water; (b) at least about 5% water-immiscible solvent; and (c) no more than 1.8% emulsifier. The aqueous cleaning composition desirably has a drop test of less than 3 seconds and/or has a vertical wicking rate of at least 0.9 cm/minute. In a further aspect, the aqueous cleaning composition may further contain between about 2% and 20% of a hydrotrope. Still further, the aqueous cleaning composition may further comprise between about 0.1% and about 20% of a humectant. In an exemplary embodiment, the porous material is a hydrophobic material such as, for example, a fabric of thermoplastic polymer fibers. Still further, a plurality of cleaning sheets may be provided in a stack and the aqueous cleaning composition distributed throughout the stack. Desirably, each cleaning sheet forming the stack contains at least 100 weight % of the aqueous cleaning composition, based upon the weight of the dry sheet.